The present invention generally relates to intravascular procedures, such as treating carotid arteries and percutaneous transluminal coronary angioplasty (PTCA), and particularly to an intravascular catheter which can be utilized in a rapid-exchange (RX) or over-the-wire (OTW) operating mode.
In typical PTCA procedures utilizing over-the-wire mode, a dilation catheter is advanced over a guide wire slidably disposed within an inner lumen of the dilation catheter into a patient's coronary artery until the balloon on the distal extremity of the dilation catheter is properly positioned across the lesion to be dilated. Once properly positioned across the lesion, the flexible, relatively inelastic dilatation balloon on the catheter is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., generally 4-20 atmospheres) to dilate the stenosed region of the diseased artery. One or more inflations of the balloon may be required to complete the dilation of the stenosis. After the last dilation, the balloon is deflated so that the dilatation catheter can be removed from the dilated stenosis and so that blood flow can resume through the dilated artery.
One significant improvement in dilatation catheters has been the introduction of rapid-exchange type dilatation catheters. These catheters have a short guide wire receiving sleeve or inner lumen extending through the distal portion of the catheter which extend from a distal guide wire port in the distal end of the catheter to a proximal guide wire port spaced proximal to the proximal end of the dilatation balloon. The proximal guide wire port is usually located at least about 10 cm. and usually not more than about 50 cm. from the distal guide wire port. A slit is preferably provided in the catheter wall which extends from the second guide wire port, preferably to a location proximal to the proximal end of the inflatable balloon to aid in the removal of the catheter from a guide wire upon withdrawal of the catheter from the patient. The structure of the catheter allows for the rapid exchange of the catheter without the need for the use of an exchange wire or adding a guide wire extension to the proximal end of the guide wire. The design of this catheter has been widely praised by the medical profession and has met with much commercial success in the market place because of its unique design. The RX type dilation catheters of the assignee for the present invention, Advanced Cardiovascular Systems, Inc., have had a significant impact in the market for rapid-exchange type dilation catheters. Such products include dilatation catheters sold under the tradenames--The Alpha, The Streak, and The Ellipse.
However, there is one significant inconvenience with the use of RX type dilatation catheter systems, namely, the inability to remove a guide wire already in place within a patient's vasculature during an angioplasty procedure without losing access to the vascular location. There has been no convenient way in which to withdraw an in-place guide wire and then advance a replacement guide wire without losing access to the location of the distal end of the RX type dilatation catheter the short guide wire receiving inner lumen in the distal extremity of a RX type dilatation catheter. These instances occur when there is a need to replace an in-place guide wire with another guide wire having a different structure, e.g., an intermediate or standard wire with a core wire which extends to the distal tip of the guide wire. The need to withdraw an in-place guide wire also occurs when the distal tip of the in-place guide wire needs to be reshaped.
U.S. Pat. No. 5,807,355 (Ramzipoor et al.), which has been assigned to the present assignee, Advanced Cardiovascular Systems, Inc., describes an intravascular catheter with both RX and OTW operative modes. The Ranizipoor et al. patent is incorporated herein by reference. While this catheter provides for RX and OTW modes of operation, which is by choice of the operating physician, only one mode may be used at a time thus limiting the effective usefulness of the device. Additionally, the Ramzipoor dual mode catheter does not provide for a smooth RX guide wire exit port for used during RX modes. During such use, the RX guide wire will deform during passage through the expanded helical coil guide wire port. The need still exists therefore for a catheter which allows for simultaneous dual mode operation and which provides for a smooth exit notch. The present invention satisfies these and other needs.